Summary of engine speed versus diff ratio

All figures assume the car is in 6th gear and has standard specification tyres:

Applicable models (manual): HSV GTS and GTS R, 2004 CV8 and VXR Monaro, 2005 CV8 Monaro

3.45:1 Engine speed @ 70 mph: 1647 rpm

3.7:1 Engine speed @ 70 mph: 1761 rpm

3.9:1 Engine speed @ 70 mph: 1857 rpm

4.1:1 Engine speed @ 70 mph: 1944 rpm

Additional table for all vehicles fitted with 4 speed auto (4L60e)

3.08: (standard) Engine speed @ 70 mph: 2000rpm

3.23:1 Engine speed @ 70 mph: 2101 rpm

3.45:1 Engine speed @ 70 mph: 2244 rpm

3.7:1 Engine speed @ 70 mph: 2434 rpm